This work was funded by the JOI/USSSP, along with partial support from NSF (OPP-9423485). I thank the Ocean Drilling Program for providing samples, M. Flower and J. Hobson for laboratory assistance, T. Whalen for technical assistance, and C. Anderson and M. Raymo for thoughtful reviews. I also thank the captain, crew, and scientific party of Leg 162 for an excellent cruise.